Assymmetric sail luff length.

greeny

greeny

Well-Known Member
Joined
15 Jun 2004
Messages
2,653
Location
Portugal
Visit site
Just in the throws of preparing to fit a top down furler with my assymmetric. To allow me to do some quick calculations and preparation without measuring on the boat, does anyone know the ball park percentage of luff length (measured cloth length) against the foil/torsion rope length of the furler. I've done some googling and got suggestions of 98% up to as much as 110%. Nothing I've found has been definite information. I know it varies depending on cut, but what do sail knowledgeable peeps on here think an approximate % would be?
 
There is no standard. It all depends on the cut of the spinnaker. A spinnaker designed for reaching will have a straighter (and therefore shorter) luff than one designed to sail at deeper angles. And even within those broad parameters every sailmaker will have his own variations. I can understand your reluctance but really you're best off taking the measurements from your boat.
 
Thanks for your replies. I always knew that I would have to actually do a measurement on the boat, but was hoping to get an approximation. If I got an approx length then I could see whether I need to raise the Halyard box up higher on the mast to take into account the length of the swivel and drum on the furler. If I do, then I need the mast down to fit new box and re route halyard. I have spoken with Z-spar who say I can raise the box up by 300mm if required but I'm trying to avoid any mast work if possible but it may be un avoidable for two reasons, one is the luff length, the other is the fact that the rig is 7/8 and the current halyard exits just above the forestay attachment. This may mean the upper swivel of the new furler is fouling the genoa furler unless I don't hoist it right up to the top leaving a foot of halyard showing. The tack is ok as its on a bowsprit.
Its looking more and more as though it is a mast down job though. Boat is only 21ft lift keel so no way I'm going up mast.
 
greeny said:
Its looking more and more as though it is a mast down job though. Boat is only 21ft lift keel so no way I'm going up mast.
Click to expand...
At that size, could you not 'bowse it down' to near horizontal, and get easy access?

After all, RN types used to do this with First-Raters in the Caribbean to replace planks and slap on fresh tar..... besides having the odd beach party with lotsa local rum!!!

And maybe... just maybe... that's one of the old RN traditions that our very own happy wanderer John Morris is likely reviving in the unspoiled islands of the Western Caribbean. ;)
 
greeny said:
Thanks for your replies. I always knew that I would have to actually do a measurement on the boat, but was hoping to get an approximation. If I got an approx length then I could see whether I need to raise the Halyard box up higher on the mast to take into account the length of the swivel and drum on the furler. If I do, then I need the mast down to fit new box and re route halyard. I have spoken with Z-spar who say I can raise the box up by 300mm if required but I'm trying to avoid any mast work if possible but it may be un avoidable for two reasons, one is the luff length, the other is the fact that the rig is 7/8 and the current halyard exits just above the forestay attachment. This may mean the upper swivel of the new furler is fouling the genoa furler unless I don't hoist it right up to the top leaving a foot of halyard showing. The tack is ok as its on a bowsprit.
It’s looking more and more as though it is a mast down job though. Boat is only 21ft lift keel so no way I'm going up mast.
Click to expand...
A furling setup on a 21 foot boat strikes me as somewhat overkill…
 
flaming said:
A furling setup on a 21 foot boat strikes me as somewhat overkill…
Click to expand...
Possibly. But just trying to extend my years of sailing life by making things a bit easier. Yes I can still manage to hoist, sail and drop it, but it's becoming more difficult as time goes on and the body complains. I sail solo all the time so being able to hoist the furler before even leaving the dock and drop it after my return has some attraction. May or may not make things easier, we'll see.
 
Chiara’s slave said:
On the plus side, if it does need mast work, all you need is a relatively high quayside and a low tide.
Click to expand...
One of my possibilities. Just got to check out the height of the quay wall to see what low water gives me and whether there's space to do it, as most of the wall is occupied by moored boats. Also will be time constrained doing it this way. Fitting a new halyard box and re routing the halyard will likely take more than an hour or two.
 
greeny said:
Possibly. But just trying to extend my years of sailing life by making things a bit easier. Yes I can still manage to hoist, sail and drop it, but it's becoming more difficult as time goes on and the body complains. I sail solo all the time so being able to hoist the furler before even leaving the dock and drop it after my return has some attraction. May or may not make things easier, we'll see.
Click to expand...
If you're talking asymmetric kite, as opposed to code sail, then they're not really designed to be left hoisted and furled. Yes people do it, but it's not in general a great idea.

Fully understand where you're coming from, but on a boat that size I'd potentially be looking at a deck mounted chute for launch and retreival, rather than a furling setup.

Something like this.

HOME | Deckchute.com
 
Stemar said:
OTOH, if you're a bit late getting it down when things get bumpy, a furler is a much nicer idea than having to go on the foredeck, all the more if you're single-handed
Click to expand...
Why would you have to go on the foredeck to drop a kite? When in cruising mode I can drop my 90sqm kite by my self without leaving the companionway.
 
flaming said:
When in cruising mode I can drop my 90sqm kite by my self without leaving the companionway.
Click to expand...
"I can do that..."

In fact, I HAVE done that. Easy.
Getting the damn thing back onto the boat by myself and back into a bag was damn hard....
 
zoidberg said:
"I can do that..."

In fact, I HAVE done that. Easy.
Getting the damn thing back onto the boat by myself and back into a bag was damn hard....
Click to expand...
As is sorting it ready for next hoist when you're alone. Hopefully on a furler this will not be a problem.
 
zoidberg said:
"I can do that..."

In fact, I HAVE done that. Easy.
Getting the damn thing back onto the boat by myself and back into a bag was damn hard....
Click to expand...
Our companionway is a long way from the kite as it comes down. Plus it’s often wet up to the numbers. We ended up getting a sock. At least it contains the damn thing, instead of having 80sq m of nylon billowing about on the tramp, with me using all 4 limbs to restrain it🤣
 
You must log in or register to reply here.

Share this page

Top